Hybrid electric vehicles having improved fuel economy over internal combustion engine and other vehicles are quickly becoming more popular as a cost of traditional fuel increases. Typically, the improved fuel economy is due to known technologies such as regenerative braking, electric motor assist, and engine-off operation.
Although the technologies improve fuel economy, there are drawbacks. One such drawback is that accessories powered by a fuel-powered engine no longer operate when the fuel-powered engine is not in operation. One major accessory that does not operate is an air-conditioning compressor, which cools air in a passenger compartment of the vehicle. Ultimately, without the use of the compressor, a temperature of the air in the passenger compartment increases to a point above a desired temperature and the fuel-powered engine of the vehicle must restart.
Accordingly, vehicle manufacturers have used a full electric compressor on hybrid vehicles. The full electric compressor operates whether the fuel-powered engine is operating or not. A significant disadvantage of the full electric compressor is the inefficiency that occurs from converting engine shaft power to electricity, then electricity back to compressor shaft power. Thus, the use of a hybrid compressor which is mechanically and electrically driven is advantageous. One such hybrid compressor is a dual drive scroll compressor described in U.S. Pat. No. 6,543,243 entitled HYBRID COMPRESSOR, hereby incorporated herein by reference in its entirety.
In order to achieve high reliability and long life of the compressor, oil is used for lubrication to minimize a wear of internal components of the compressor. In addition to lubricating the compressor, the oil also carries away heat and performs a sealing function, particularly between mating surfaces.
The oil is typically stored in an oil reservoir disposed in the compressor, and transported in the compressor unit with a refrigerant. However, it is desirable that the oil contained in the refrigerant be separated before leaving a housing of the compressor, so that the oil may flow back into the oil reservoir. Prior art oil separators, such as cyclone separators, which include filtering means and spaces to reduce the velocity of flow, are known in the art.
U.S. Pat. No. 6,874,328 entitled HYBRID COMPRESSOR DEVICE, hereby incorporated herein by reference in its entirety, discloses an oil separating unit. The oil separating unit is a funnel-shaped member adapted to cause a swirling movement of a refrigerant. Such swirling movement applies a centrifugal force to a lubricating oil contained in the refrigerant, thereby separating the lubricating oil from the refrigerant. An outer periphery of the funnel-shaped member contacts an inner wall of an oil storage chamber and is affixed thereto.
U.S. Pat. No. 7,264,453 entitled HORIZONTAL SCROLL COMPRESSOR HAVING A CONNECTING PASSAGE ON THE OPPOSITE SIDE OF A SUCTION PORT FOR CONNECTING A MOTOR ACCOMMODATING CHAMBER WITH A SUCTION CHAMBER, hereby incorporated herein by reference in its entirety, discloses an oil separator for separating a lubricating oil from a high pressure refrigerant gas. The oil separator is a hollow member having a passageway formed therethrough. The passageway facilitates the flow of the high pressure refrigerant gas to a discharge port. The oil separator is disposed in a discharge chamber of a compressor, wherein the discharge chamber includes a reservoir to accumulate the separated lubricating oil.
It is also desirable that during operation of the compressor, a noise generated thereby which is perceptible by passengers of the vehicle is minimized. Operating noise is primarily caused by pressure pulsations associated with compression. In practice, different structures are used for reducing the pressure pulsations, such as chambers where pressure waves are attenuated by expansion.
U.S. Patent Application Publication No. 2007/0175239 entitled REFRIGERANT COMPRESSOR, hereby incorporated herein by reference in its entirety, discloses a compressor having an oil separation structure. The separation structure includes a plurality of separation chambers for separating a lubricating oil from a refrigerant gas. The separation chambers are in fluid communication with a muffler chamber. An expansion type muffler effect of the muffler chamber attenuates variation in pressure waves of the refrigerant gas.
Although the aforementioned structures operate effectively, the structures involve higher manufacturing costs. Additionally, the structures are complex, heavy, and are difficult to package in small engine bays of hybrid vehicles.
Accordingly, it would be desirable to produce a fluid separator for a compressor, wherein an attenuation of pressure pulsations and a separation of a fluid flowing therethrough are maximized and a cost, complexity, and space requirement thereof are minimized.